The present invention generally relates to a call charging (or accounting) method in a radio telephone system accommodating a radio telephone. More specifically, the present invention is directed to such a call charging process that a telephone call is issued to a public telephone network by using a nearby radio controller, even when a user of a radio telephone moves into a home, a street, or on the premises of a firm or company, and in particular when a telephone call is made to the public telephone network (PBX) via a radio controller installed in a private branch exchange on the premises of a company.
In a radio telephone system combining a radio telephone with a radio controller, when the user of the radio telephone issues a telephone call by using the radio controller installed in the PBX on the premises of the company, the call charge process at the side of public telephone network is performed with respect to the telephone calling line of the PBX. As a result, when another user of a radio telephone who is a person other than the subscriber originally present with this company, issues a telephone call to the public telephone network via the radio controller on the premises of the firm, in case that the PBX allows this telephone call, the call charge for this telephone call is charged on the PBX side. As a consequence, it is common to prohibit such an external use of the radio telephone.
On the other hand, as a method for charging the call account to all terminals (telephones), it has been proposed as recited in JP-A-3-91356 that when the telephone calls are issued from the parent station with the different radio telephones, personal numbers are sent from the radio telephones, and the call accounts are charged to the respective personal numbers.
In the above-described prior art, for instance, the call account charged to the terminal which issues the telephone call via a PBX to the public telephone network, is processed in such a manner that either all the call account processings at the side of public telephone network are performed for the telephone call originating lines installed in the PBX of the public telephone network, or all the call accounts are charged to the call originating terminals. As a result, the prior art radio controllers installed in the firm have been so arranged to allow only use of radio telephones which have been previously registered therein. Thus, any person who comes from outside the company must borrow the inter-nal-use radio telephone. Otherwise, another radio controller for the public telephone network must be employed in addition to the existing radio controller in order to accept a telephone call from a radio telephone externally transported or moved in from outside.